1. Field of the Invention
This invention relates to tape cassettes and, more particularly, to a tape cassette for use with video tape recorders (VTR) and the like.
2. Background of the Invention
In a tape cassette used with a VTR, a magnetic tape in a cassette housing runs from a supply reel in the cassette housing, to a rotary magnetic head assembly in the body of the VTR, and back to a take-up reel in the cassette housing. The length of tape that contacts the head assembly in the VTR is outside the cassette housing and is exposed when the cassette is not in use. If that exposed length of tape becomes slack when the cassette is not in use, the loading mechanism for winding the magnetic tape around the rotary magnetic heads in the VTR can malfunction, preventing the magnetic tape from loading properly. At best, the VTR will not operate; at worst the tape can be damaged or ruined. Moreover, the slack length of tape protruding from the cassette is more susceptible to damage when the cassette is being handled.
Prior art tape cassettes use resilient braking strips to brake the tape as it travels to and from the tape reels and to avoid undesirable slack in the exposed length of tape. The tape engages a pair of spaced guide pins between each tape reel and an opening in the cassette housing. The cassette has two resilient braking strips, one associated with each pair of guide pins, and each resilient strip has a free end that is resiliently urged to extend across the space between the respective guide pins and thus contacts a face of the tape spanning the space between the respective guide pins. When the tape is running, it is pulled tight between the paired guide pins, which pushes the free end of each resilient braking strips against the biasing force of the latter. When the tape is not running, and hence is not tensioned, each resilient strip extends across the space between the respective pair of guide pins and is intended to press the tape against one of the respective guide pins to brake or frictionally resist movement of the tape therebetween. The free end portion of each resilient braking strip also pushes against the tape when the latter is tensioned while running so as to avoid undesirable slack in the tape in that condition.
However, a significant shortcoming of the above arrangement is that it becomes less effective as the cassette gets older. When the cassette is new, the resilient braking strip has sufficient resilience to prevent movement of the tape by pressing the tape against a guide pin when the cassette is not in use. However, as the cassette gets older, the braking strip, because it flexes each time the tape slackens and tightens, loses its resilience. Thus, the braking strip no longer bears with sufficient force against a guide pin and does not provide enough braking force when the cassette is not in use.